<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>

 <style>
    .box{
        width: 200px;
            height: 200px;
            background-color: green;
            box-shadow: 0 10px 10px;
            border-radius: 10px;
            animation: breath 2700ms ease-in-out 0s infinite alternate ;
            margin: 0 auto;
    }
    @keyframes breath {
        /* opacity 透明度 */
        0%{
            opacity: 0.2;
            box-shadow: 0 1px 2px rgb(165, 98, 98,0.1);
        }
        50%{
            opacity: 0.6;
            box-shadow: 0 1px 2px rgb(80, 206, 118,0.76);
        }
        100%{
            opacity: 1.0;
            box-shadow: 0 1px 2px rgb(182, 98, 98,1);
        }


    }
 </style>
</head>
<body>
    <div class="box"></div>
</body>
</html>